(Background: Europe, 230/240V with DIN-Rail contactor)

I have a few circuits that use contactors to control lighting. Some of the contactors are wired so that the push-button provides Neutral, others are wired for Phase. I have now added relay outputs on my EasyDAQ board as push buttons on the contactors so I can control them from Indigo (Thanks for the EasyDAQ plugin). All of this works as expected.

Here is my issue. Because the contactor push-button is a toggle, and there are several push-buttons (other than the EasyDAQ board) on each circuit, I can never know the On/Off state of the circuit without actually looking at a lamp (which might be in the pool or the yard somewhere).

I do have a partial solution... In one case, the contactor controls a multi pole relay and I was able to use an unused set of relay contacts to control an input to the EasyDAQ, so I can now "see" the circuit state in Indigo.

However, in other cases, there is no relay and the contactor is in a remote panel (though I do have access to the control leads at the EasyDAQ). In one case, the contactor controls a 12v transformer and I guess I could feed that back to an EasyDAQ input. But, the contactor panel is about 70M away from the EasyDAQ and there is no signaling wire available.

So, finally, my question: Does anyone know of a way to signal over the control leads so that I can then pickup the signal by the EasyDAQ and generate a closure on an EasyDAQ input (probably via an external relay). If necessary, I can change the control wiring from Neutral to/from Phase.